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Line 86: − <br> − − ==To calculate the required storage reservoir depth, where the area of the facility is constrained (3D drainage)== − On densely developed sites the surface area of the facility may be constrained, in this case the required water storage reservoir depth of the bioretention cell or infiltration trench, d, can be calculated assuming three dimensional drainage as follows: − :<math>d=a[e^{\left ( -bD \right )} -1]</math> − Where − <math>a=\frac{Ar}{x}-\frac{i Ai}{x f'}</math> − and − <math>b=\frac{xf'}{nAr}</math> − − (The rearrangement to calculate the required footprint area of the facility for a given depth using three dimensional drainage is not available at this time. Elegant submissions are invited.)<br>
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In many locations throughout Ontario, there may be limited depth of soil available into which stormwater may be infiltrated. In such cases the required storage needs to be distributed more widely across the landscape. The footprint area of the water storage reservoir, A<sub>r</sub> can be calculated:
In many locations throughout Ontario, there may be limited depth of soil available into which stormwater may be infiltrated. In such cases the required storage needs to be distributed more widely across the landscape. The footprint area of the water storage reservoir, A<sub>r</sub> can be calculated:
<math>Ar=\frac{iDAi}{nd+f'D}</math>
<math>Ar=\frac{iDAi}{nd+f'D}</math>
==To calculate the required storage reservoir depth, where the area of the facility is constrained (3D drainage)==
On densely developed sites the surface area of the facility may be constrained, in this case the required water storage reservoir depth of the bioretention cell or infiltration trench, d, can be calculated assuming three dimensional drainage as follows:
:<math>d=a[e^{\left ( -bD \right )} -1]</math>
Where
<math>a=\frac{Ar}{x}-\frac{i Ai}{x f'}</math>
and
<math>b=\frac{xf'}{nAr}</math>
(The rearrangement to calculate the required footprint area of the facility for a given depth using three dimensional drainage is not available at this time. Elegant submissions are invited.)<br>
<br>
==Time required to drain surface ponded water==
==Time required to drain surface ponded water==
==Time to drain the storage reservoir==
==Time to drain the storage reservoir==
The target [[drainage time]] for the active storage reservoir depth of an infiltration facility is typically between 48 and 72 hours or based on the average inter-event period for the location. Contact the local municipality or conservation authority for criteria. See [[Drainage time]] for more information about how inter-event periods vary across Ontario and to help select what is suitable for the site. <br>
The target [[drainage time]] for the active storage reservoir depth of an infiltration facility is typically between 48 and 72 hours or based on the average inter-event period for the location. Contact the local municipality or conservation authority for criteria. See [[Drainage time]] for more information about how inter-event periods vary across Ontario and to help select what is suitable for the site. <br>
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Try the Darcy drainage time calculator tool for estimating the time required to fully drain the water storage reservoir of the facility assuming either one or three-dimensional drainage: <br>
Try the Darcy drainage time calculator tool for estimating the time required to fully drain the water storage reservoir of the facility assuming either one or three-dimensional drainage: <br>